1. Field of the Invention
The present invention relates to a slider mounted silicon chip with an integrated electronic structure that includes a magnetoresistive (MR) sensor and associated circuitry, and more particularly to a silicon chip including an integrated MR head which is mounted to a trailing edge of a slider wherein the silicon chip contains integrated circuits, such as electrostatic discharge (ESD) circuits, which serve the MR sensor of the MR head.
2. Description of the Related Art
MR sensors are commonly used as read elements in thin film magnetic heads for sensing recorded signals on a magnetic medium, such as a magnetic disk. A thin film magnetic head which incorporates an MR sensor is called an MR head. An MR sensor includes a thin stripe of conductive material, such as "Permalloy" (NiFe). When a magnetic medium, such as a magnetic disk, is rotated adjacent the MR sensor, magnetic fields from the medium induce a response in the MR sensor causing the sensor to change its resistance. A sense current conducted through the MR sensor changes its magnitude proportionally to the change in resistance. The magnitude changes are then processed by channel electronics into playback signals representing information stored on the magnetic medium.
A typical MR stripe is 5 microns long, 1 micron high and 200 Angstroms thick. The length and thickness of the MR stripe are exposed at a surface of an MR head while the height is buried in the head body. During construction and assembly of the MR head, the MR stripe must be protected from electrostatic discharge (ESD) and/or electrical overstress (EOS). A discharge or impulse of only a few volts can destroy or severely damage the MR stripe. Such a discharge can occur by contact with or close proximity to a person, plastic involved in the fabrication, or components of a magnetic medium drive.
The prior art teaches the use of electrical elements to protect MR stripes from ESD and EOS. These elements include diodes which shunt excessive current away from the MR stripe to larger conductive components in the head via leads which are connected to the MR stripe. Such larger components may include shield or coil layers that form part of an integrated MR head.
ESD protection devices and MR heads have been fabricated on sliders. Standard materials in the industry for sliders have been ceramic materials, such as titanium carbide (TIC) and N58, a combination of TiC and aluminum oxide (Al.sub.2 O.sub.3). Both N58 and TiC are wear resistant and easy to machine. However, ESD diodes and other circuit components, with the sensitivity and robustness required to protect an MR stripe from ESD, cannot be produced in either TiC or N58. Nevertheless, it is known that very sensitive diodes can be fabricated on a silicon water.
There is a strong felt need in the art to improve the ESD protection of MR stripes to the level of that provided by silicon diodes without changing the slider material from N58. Two technical challenges are involved. One is fabrication of magnetic heads on N58 sliders with thin film technology and the other is the construction of protection elements on a silicon wafer by integrated circuit technology. It would be desirable if these two technologies could be merged to provide an MR head on a slider, such as N58, which is protected from ESD by silicon elements. Further, it would be desirable if a method of fabrication could be provided which combines the two technologies for mass producing MR heads on sliders with ESD protection.